A module in Ruby is a collection of methods and constants. The scope of these methods or constants is limited to the module they are declared in.
Let us explore what we can do with modules.
If we look at the program described below:
module Coffee
def cappuccino
puts "cappuccino!"
end
endmodule Tea
def chai
Puts “chai!”
End
endclass Beverage
include Coffee
Include Tea
def soda
puts "soda!"
end
endb = Beverage.new
b.cappuccino # => "cappuccino!"
b.chai # => "chai!"
b.soda # => “soda!”
With the object ‘b’ of class ‘Bird’, we can now access both methods, flippers and wings.
This is made possible by the usage of the include keyword that evaluates the module code in the context of the class.
Modules and Class Composition
If we look at the example mentioned above, we see that a single class has included more than one module. Effectively giving object b access to methods of more than one module apart from its own methods.
Using Extend
module Coffee
def cappuccino
puts "cappuccino!"
end
endclass Beverage
extend Coffee
def soda
puts "soda!"
end
endb = Beverage.new
b.cappuccino # => "NoMethodError"
b.soda # => “soda!”
Beverage.cappuccino # => “cappuccino!”
